Portable communication devices, such as mobile phones, personal digital assistants (PDAs) and tablets have become extremely popular and for many users are now considered indispensable.
One of the most important components of portable communication devices (hereinafter referred to as “UE”s) are their antennas, which are configured to radiate and receive electromagnetic waves so as to transmit and exchange wireless information signals between the UE and other locations. Such antennas must be designed to work with multiple frequency bands such as those used in present day wireless communication networks. Wireless communication device users continue to demand increasingly thinner, lighter and miniaturized devices. Such demands place additional physical limitations on the antennas used in portable wireless communication devices. As a result, multi-band antenna design for mobile communication devices continues to become more complex.
The housings of portable communication devices or user equipment (UE) may accommodate one or more antennas that support wireless communications. A UE may use long-range wireless communication systems such as cellular telephone systems, to send and receive communications. Such cellular or other long-range wireless communication systems may include, the Global System for Mobile Communications (GSM) telephone bands, Enhanced Data rates for GSM Evolution (EDGE); General Packet Radio System (GPRS); CDMA, such as IS-95; CDMA2000; WCDMA or Universal Mobile Telecommunications System (UMTS); Fourth Generation Long Term Evolution (LTE); other wide area network communication systems; PrivateMobile Radio (PMR); Worldwide Interoperability for Microwave Access (WIMAX); WLAN; other 3G or 4G networks; or the like. UEs may also use short-range wireless communication protocols to support communications with nearby devices. Such short rang protocols may include Wi-Fi (IEEE 802.11) and Bluetooth protocols.
The positioning and placement of antennas in UEs having smaller and thinner housings present additional design challenges. Handheld communication devices have largely abandoned antenna designs that have an antenna projecting outward from the housing. Mobile communication device housings are now routinely designed with internal antenna elements. However, when antennas are positioned within or and along an edge of the device housing, the presence of a user's hand can degrade antenna performance. Regardless, antennas are routinely located along an inner edge of the device housing despite the increased likelihood of these detrimental effects.
Additionally, when an antenna is included as part of an exterior surface of a UE chassis, the touch of a user's hand may also establish a low impedance bridge between the exterior antenna and a grounded exterior section of the UE chassis. Such a low impedance bridge can be detrimental to the efficiency and operation of the UE's ability to transmit and received radio frequency (RF) signals.